Ionic serve fail after upgrade to ionic cli v3

i upgrade the ionic cli to v3 as this blog said http://blog.ionic.io/announcing-ionic-cli-v3/,

but when i run ionic serve in my project, it blocked and stop running.

Below is my output when i run ionic sever --verbose:

> [ERROR] Error occurred while loading plugins. CLI functionality may be limited.
>         Checking for CLI updates now...
> [DEBUG] Plugin error: FILE_INVALID_JSON
> [DEBUG] Checking for latest plugin version of ionic@latest.
> "3.0.0"

> [DEBUG] Latest version of ionic@latest is .
> [DEBUG] !!! ERROR ENCOUNTERED !!!
> SyntaxError: Unexpected end of JSON input
> [DEBUG] SyntaxError: Unexpected end of JSON input
>             at Object.parse (native)
>             at /Users/boutell/npm/lib/node_modules/ionic/node_modules/@ionic/cli-utils/dist/lib/plugins.js:212:36
>             at next (native)
>             at fulfilled (/Users/boutell/npm/lib/node_modules/ionic/node_modules/@ionic/cli-utils/dist/lib/plugins.js:4:58)

And my `ionic info` is:
> [ERROR] Error occurred while loading plugins. CLI functionality may be limited.
>         Checking for CLI updates now...
> [ERROR] No updates found after plugin error--please report this issue.

> global packages:

>     @ionic/cli-utils : 1.0.0
>     Ionic CLI        : 3.0.0

> System:

>     Node       : v6.10.1
>     OS         : macOS Sierra
>     Xcode      : Xcode 8.3 Build version 8E162
>     ios-deploy : 1.8.1
>     ios-sim    : 5.0.6

What't wrong with my project?